U.S. patent number 5,297,443 [Application Number 07/909,960] was granted by the patent office on 1994-03-29 for flexible positioning appendage.
Invention is credited to John D. Wentz.
United States Patent |
5,297,443 |
Wentz |
March 29, 1994 |
Flexible positioning appendage
Abstract
A flexible appendage for use as a robot arm, controllable
medical instrument, or simply a toy, has flexibly coupled segments
defining an open lumen, and flanges protruding laterally of the
axis. The flanges have passages for control lines spaced laterally
from the axis. Each control line is fixed to a segment and can be
pulled through the other segments from the proximal end. The
control lines shorten a lateral side of the appendage to
controllably bend it. Resilient couplings between the segments,
leave open the lumen for passage of conduits or tools. The
couplings can be helical springs wound with turns which abut at
rest, such that the couplings elongate on the outside of a bend but
do not compress on the inside, thereby maintaining the overall
length of the appendage. The control lines are distributed around
the axis, and can be arranged in ranks for controlling groups of
the segments at different distances from the proximal end. The
springs coupling proximal segments are more rigid than for distal
segments, and the segments can be smaller and/or longitudinally
shorter approaching the distal end.
Inventors: |
Wentz; John D. (Brooklyn,
NY) |
Family
ID: |
25428108 |
Appl.
No.: |
07/909,960 |
Filed: |
July 7, 1992 |
Current U.S.
Class: |
74/490.04;
901/21; 446/27; 446/390; 600/104; 600/139 |
Current CPC
Class: |
B25J
15/12 (20130101); B25J 18/06 (20130101); B05B
15/652 (20180201); A61B 34/70 (20160201); A61B
34/71 (20160201); A61B 2017/00323 (20130101); A61B
2017/2905 (20130101); A61B 2017/2927 (20130101); A61B
2034/301 (20160201); A61B 34/30 (20160201); A61B
2034/742 (20160201); Y10T 74/20323 (20150115) |
Current International
Class: |
A61B
19/00 (20060101); B25J 18/00 (20060101); B25J
18/06 (20060101); B25J 15/12 (20060101); B05B
15/06 (20060101); B05B 15/00 (20060101); A61B
17/28 (20060101); G05G 011/00 (); B25J
018/06 () |
Field of
Search: |
;74/479 ;128/4
;446/27,368,390 ;604/95 ;901/21 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
871786 |
|
Oct 1981 |
|
SU |
|
1256955 |
|
Sep 1986 |
|
SU |
|
1301701 |
|
Apr 1987 |
|
SU |
|
Primary Examiner: Herrmann; Allan D.
Attorney, Agent or Firm: Eckert Seamans Cherin &
Mellott
Claims
I claim:
1. A flexible positioning appendage, comprising:
a plurality of segments, aligned to define a longitudinal axis of
the appendage, each of the segments having at least one opening
spaced laterally of the axis, defining a passage substantially
parallel to the longitudinal axis;
resilient couplings spacing the segments; and,
at least one control line having an end fixed to a remote one of
the segments, spaced from a proximal end of the appendage, the
control line passing through the passage of each of the segments
between the remote segment and the proximal end, whereby tension on
the control line causes the appendage to bend laterally toward the
control line;
wherein each of the segments defines an open lumen substantially
along the longitudinal axis, and wherein the resilient couplings
are hollow tubular structures, aligned with the lumen of the
segments; and,
wherein the tubular resilient couplings between respective ones of
the segments have different rigidities.
2. The flexible positioning appendage according to claim 1, wherein
the segments have a plurality of passages distributed around the
axis, and further comprising a plurality of control lines, whereby
the appendage is bendable in opposed directions by tension on
selected ones of the control lines.
3. The flexible positioning appendage according to claim 2, wherein
the control lines are arranged in ranks for controlling groups of
the segments at different distances from the proximal end, at least
one rank of control lines being fixed to a relatively more proximal
segment than at least one other rank of control lines.
4. The flexible positioning appendage according to claim 3, wherein
at least one of said ranks of segments is joined to a plurality of
separated appendages defining a next successive rank.
5. The flexible positioning appendage according to claim 1, wherein
at least one of dimensions of the segments and flexibility
characteristics of the resilient couplings vary along the appendage
to form at least one area of preferential bending.
6. The flexible positioning appendage according to claim 5, wherein
the area of preferential bending is at a distal end of the
appendage.
7. The flexible positioning appendage according to claim 1, further
comprising a surface material disposed over the segments.
8. The flexible positioning appendage according to claim 1, further
comprising means for limiting a minimum bending radius between
adjacent segments including at least one of a sheath on a control
line extending through at least a portion of a segment and a spacer
protruding between adjacent segments.
9. The flexible positioning appendage according to claim 1, further
comprising sheaths enclosing the control lines over at least a
portion of the appendage, and wherein the sheaths are one of
compressible and gapped, for allowing foreshortening of a lateral
side of the appendage to achieve bending.
10. A flexible positioning appendage, comprising:
a plurality of segments, aligned to define a longitudinal axis of
the appendage, each of the segments having at least one opening
spaced laterally of the axis, defining a passage substantially
parallel to the longitudinal axis;
resilient couplings spacing the segments; and,
at least one control line having an end fixed to a remote one of
the segments, spaced from a proximal end of the appendage, the
control line passing through the passage of each of the segments
between the remote segment and the proximal end, whereby tension on
the control line causes the appendage to bend laterally toward the
control line;
wherein each of the segments defines an open lumen substantially
along the longitudinal axis, and wherein the resilient couplings
are hollow tubular structures, aligned with the lumen of the
segments;
wherein each one of the segments comprises a tube disposed along
the axis and at least one flange plate aligned perpendicular to the
tube, the resilient tubular couplings being coupled to the tube of
adjacent ones of the segments; and,
wherein each segment has two flange plates, the tube protruding
from the flange plates at opposite ends of the segment.
11. The flexible positioning appendage according to claim 10,
wherein the tubular resilient couplings comprise helical
springs.
12. The flexible positioning appendage according to claim 10,
wherein the segments are of different lengths along the appendage,
at least some of the segments at a more proximal position along the
appendage having a greater spacing between the flange plates than
segments at a more distal position.
13. A flexible positioning appendage, comprising:
a plurality of segments, aligned to define a longitudinal axis of
the appendage, each of the segments having at least one opening
spaced laterally of the axis, defining a passage substantially
parallel to the lnogitudinal axis;
resilient couplings spacing the segments; and,
at least one control line having an end fixed to a remote one of
the segments, spaced from a proximal end of the appendage, the
control line passing through the passage of each of the segments
between the remote segment and the proximal end, whereby tension on
the control line causes the appendage to bend laterally toward the
control line; and,
wherein each of said segments comprises axially spaced flanges,
coupled together to form a rigid segment structure.
14. A flexible positioning appendage, comprising:
a plurality of segments, aligned to define a longitudinal axis of
the appendage, each of the segments having at least one opening
space laterally of the axis, defining a passage substantially
parallel to the longitudinal axis;
resilient couplings spacing the segments; and,
at least one control line having an end fixed to a remote one of
the segments, spaced from a proximal end of the appendage, the
control line passing through the passage of each of the segments
between the remote segment and the proximal end, whereby tension on
the control line causes the appendage to bend laterally toward the
control line;
wherein each of the segments defines an open lumen substantially
along the longitudinal axis, and wherein the resilient couplings
are hollow tubular structures, aligned with the lumen of the
segments;
wherein the tubular resilient couplings comprise helical springs;
and,
wherein at least some of the helical springs are wound such that
adjacent turns of springs rest against one another at rest, the
adjacent turns resting against one another on a side of the
appendage facing toward a bending radius, defining a constant
length, and separating on a side of the appendage facing away from
the bending radius, to allow bending.
15. The flexible positioning appendage according to claim 14,
wherein each of the segments comprises a tube disposed along the
axis and at least one flange plate aligned perpendicular to the
tube, the springs being coupled to the tubes of adjacent ones of
the segments.
16. The flexible positioning apparatus according to claim 14,
wherein the segments comprise axially spaced flanges, coupled to
permit at least some tilting of the flanges.
17. The flexible positioning appendage according to claim 14,
further comprising a potting material molded over the segments.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of elongated flexible
structures having longitudinally operable tension or extension
mechanisms spaced laterally of a central axis such that the
flexible structures can be moved into a curved configuration by
applying relatively more longitudinal tension or extension on one
side of the axis than the other. More particularly, the invention
concerns such a structure wherein a plurality of rigid segments,
which are preferably coupled by closed helical springs that space
flanged ends of the segments, are provided with control lines for
exerting tension between a proximal end of the structure and at
least one segment spaced from the proximal end.
2. Prior Art
Controllably bendable resilient structures are known, with segments
coupled to define a longitudinal extension, and control lines
passing through the segments at points spaced laterally of a
central axis. An example is a toy snake which can be curved by
shortening one of three laterally spaced control lines as disclosed
in U.S. Pat. No. 2,241,576--Barton. The segments must be structured
or connected to allow adjacent segments to tilt relative to one
another along the axis. In Barton the segments have convex end
surfaces which rest against one another at a point. The control
lines extend freely through the segments from manually engageable
finger rings (at the tail of the snake). The control lines can be
pulled through the segments relative to their terminus at the last
segment (the head) remote from the rings. By exerting unequal
tension on the three laterally spaced control lines it is possible
to cause the snake to bend, e.g., to rear its head. In so doing,
the point at which adjacent segments contact one another moves
laterally toward the inside of the curve. The segments are not
connected mechanically to one another except by virtue of being
strung like beads on the control lines.
Variations of the idea of curved segments and lateral control lines
are disclosed, for example, in U.S. Pat. Nos. 4,393,728 and
4,494,417--both to Larson et al, in connection with a robot
painting arm. U.S. Pat. No. 3,266,059--Stelle discloses a similar
curved abutting surface in an articulated elbow joint between rigid
members of a robot arm.
A variably flexible tether is disclosed in U.S. Pat. No.
3,546,961--Marton. A control cable passes through adjacent segments
having concave and convex abutting surfaces. When tension is
applied, the segments are pulled against one another and the device
becomes relatively more rigid. When tension is released the device
is flaccid. The convex/concave abutment between adjacent segments
defines the degree of freedom of bending between the segments.
With non-compressible segments abutting at curved surfaces, such
devices curve by tension on a control line at the lateral inside of
the curve but do not become foreshortened longitudinally. This is
because facing parts of the adjacent non-compressible segments
remain in contact. The extent of possible bending is defined by the
particular structure of the adjacent segments, i.e., by the extent
of tilting available until portions of the segments spaced
transversely from the longitudinal axis come into contact on the
inside of the curve.
Arrangements which have compressible segments or a compressible
element between non-compressible segments are relatively
foreshortened when tension is applied and elongated when tension is
released. Examples are shown in U.S. Pat. Nos. 3,060,972--Sheldon
and 4,551,061--Olenick. In U.S. Pat. No. 4,712,969--Kimura, an
extensible-retractable arm is provided wherein individually driven
expansion-contraction elements are provided between each of the
segments.
An important objective in a robot arm or similar controllable
appendage is to accurately control the position of the distal end.
A welding tool, spray head, grasping apparatus, video camera or any
of various other structures can be mounted on the arm, and oriented
or manipulated (e.g., applied to a workpiece) in a programmed
manner. However, an arm comprising non-compressible segments with
curved abutting faces is difficult to control accurately and to
keep suitably stiff because there is no real connection between the
adjacent segments. On the other hand, the longitudinal expansion
and contraction inherent in resiliently coupled segments, which
varies as tension is applied or changed to achieve a particular
curve, makes accurate position programming difficult or
impossible.
In U.S. Pat. Nos. 3,497,083--Anderson et al and 4,566,843--Iwatsuka
et al, segments are coupled by universal joints between adjacent
segments, defined by pivot axes oriented at right angles. These
joints are non-compressible, but are heavy, complicated and
expensive. Additionally, the joint structures eliminate the
potential of an open lumen along the central axis of the arm, for
passage of fluid lines and/or electrical lines, or at least
substantially occlude the available space for such lines.
Assuming the flexible structure is applied to a device for
positioning a free distal end, for example carrying a tool, the
load to be borne by segments disposed closer to the proximal end is
greater than the load for segments at the distal end because the
proximal segments must carry the weight of the distal segments.
Anderson and Iwatsuka use progressively smaller segments or groups
of segments proceeding toward the distal end. Each also provides
separate control lines for the different segments or groups. The
control lines for the larger, proximal segments are more laterally
spaced than those for the smaller, distal segments, which enables
greater leverage to be applied to generate a proximal curve.
In Anderson and Iwatsuka the maximum limit of the curve available
between adjacent segments (i.e., the minimum radius of curvature)
is reached when the segments abut one another at contact points
located at a lateral space from the center of the universal joint
along the longitudinal axis. The universal joint defines a secure,
if heavy, means for fixing the alignment of adjacent segments. This
security of alignment, however, has the unfavorable result that
when first applying tension to a control line, only the endmost
segment attached to the control line, generally the closest
proximal segment, becomes tilted relative to the next adjacent
segment. This adjacent segment is not urged to tilt until the more
proximal segment curves to reach the contact point defining its
limit. With increasing tension, the curve of the arm as a whole
begins with tilting of segments exclusively at the base or proximal
area, and proceeds outwardly, segment by segment, as each of the
segments in turn is curved to its limit.
It would be advantageous to provide a flexible positioning
appendage which has good flexibility and bends in a continuous
manner along its length, but which has sufficient structural
integrity to support itself, plus a load on the free or distal end.
The appendage should be controllably bendable at any area (or even
individual joint) along its length, independent of curves at other
areas. Preferably, this should be achieved in a device which
defines a passageway for fluid or electrical lines and the like,
and does not necessarily contract or elongate when tension is
applied and released. Generally, it is desirable to provide for
progressively greater stiffness and support proceeding towards the
proximal end, however, a given application may require the
capability of a pronounced bend at a certain point along the
appendage. This is provided according to the invention by certain
arrangements of resilient couplings and resilient segments,
facilitating an appropriate selection of rigidity vs. flexibility
which is apt for a number of applications as discussed in detail
hereinafter.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a low cost flexible
positioning appendage which provides a maximum of flexibility and
control with a minimum of structural complexity or weight.
It is another object of the invention to provide such an appendage
which can be arranged when required to bend smoothly and
continuously along its length, or to define preferential bend
points which with increasing control line tension will tend to bend
first.
It is also an object of the invention to provide a resilient
coupling which spaces the segments in a flexible positioning
appendage, but is not subject to variations in elongation as a
result of tension applied to achieve position control.
It is a further object of the invention to provide a positioning
appendage which is apt for a variety of diverse applications.
It is another object of the invention to provide a positioning
appendage having a particular layout for the control lines which
enables better operational control when the arm is cantilevered
(i.e., extended substantially horizontally from a base).
It is still another object of the invention to enable the selection
of structural parameters for segments and couplings between
segments which can be chosen to enable either task-specific
preferred bending points or generally equal bending along the
length of the appendage.
It is a further object to provide a controllable appendage which
can mimic the operation of animal appendages such as fingers,
hands, elephant trunks, antennae, tails, tongues, etc., and are
readily provided in the necessary size and shape to resemble such
animal appendages, including the skeletal structures under the
skin.
These and other objects are accomplished by a flexible appendage
for use as a robot arm, controllable medical instrument, or simply
a toy. The device has flexibly coupled segments preferably defining
an open lumen, each segment having one or more flanges protruding
laterally of a centerline or axis. The flanges have passages for
control lines spaced laterally from the axis. Each control line is
fixed at one end to a segment and can be pulled through the other
segments from the other (proximal) end. With unequal tension, the
control lines shorten a lateral side of the appendage to
controllably bend the appendage as desired. Resilient couplings
between the segments, leave open the lumen for passage of conduits
or tools. The couplings can be helical springs wound with turns
which abut at rest, such that the couplings can elongate on the
outside of a bend (as the spring turns separate) but cannot
compress on the inside of the bend, thereby maintaining a constant
overall length of the appendage notwithstanding changes in control
line tension. The control lines are distributed around the axis,
and can be arranged in ranks for controlling groups of the segments
at different distances from the proximal end. The springs coupling
proximal segments can be more rigid than for distal segments, and
the segments can be smaller and/or longitudinally shorter
approaching the distal end.
BRIEF DESCRIPTION OF THE DRAWINGS
There are shown in the drawings exemplary embodiments of the
invention as presently preferred. It should be understood that the
invention is not limited to the precise arrangements and
instrumentalities shown and discussed, and is capable of variation
in accordance with the scope of the appended claims and their
reasonable equivalents. In the drawings,
FIG. 1 is a perspective view illustrating a flexible positioning
appendage in accordance with the invention, the appendage shown
cantilevered from its base (i.e., extending horizontally);
FIG. 2 is perspective view corresponding to FIG. 1, wherein the
appendage is curved into a continuous arc;
FIG. 3 is an elevation view showing a section along an embodiment
of the invention having abutting-turn segment coupling springs;
FIG. 4 is an elevation view corresponding to FIG. 3, with the
section curved;
FIGS. 5 through 7 are perspective illustrations showing some
alternative segment structures;
FIG. 8 is an elevation view illustrating application of the
invention to a device for positioning a medical instrument;
FIG. 9 is a perspective view illustrating application of the
invention to a toy monster mask having movable mandible
structures;
FIG. 10 is an elevation view, partly in section, showing a means
for driving the appendages provided in the mask of FIG. 9;
FIG. 11 is a section view through an electrically driven embodiment
including a controller;
FIG. 12 is an exploded perspective view illustrating a preferred
segment structure for a pentagonal arrangement of ranked control
lines;
FIG. 13 is an elevation view illustrating ranked control lines
operable independently to bend different subsections along the
longitudinal axis;
FIG. 14 is a perspective view of an embodiment having a skin
structure disposed over segments, arranged for controlling the aim
of a garden hose;
FIG. 15 is a partial elevation view showing joints formed with open
springs, rendering the appendage longitudinally compressible;
FIG. 16 is a partial elevation view wherein the bending radius is
limited by control wire sheaths in a Bowden cable like
arrangement;
FIG. 17 is a partial elevation view wherein the bending radius is
limited by protrusions of the segments;
FIG. 18 is a partial cutaway view showing application of the
segments to simulate a human hand, including a metacarpal area
wherein a plurality of the distally-separate appendages (phalanges)
are joined so as to be bendable as a unit;
FIG. 19 is a partially cut away elevation view showing an
alternative form of medical instrument having a preferential distal
bending area; and,
FIG. 20 is a perspective view of a boxing toy.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in a horizontal orientation in FIG. 1, and in an upwardly
curved orientation in FIG. 2, the invention is a flexible
positioning appendage or arm 30, comprising a plurality of
resiliently coupled rigid segments 40 which can be pulled into a
curve using control lines 50. Each of the segments 40 preferably
defines an open lumen 62 along a longitudinal axis 64 of the
appendage 30, and has at least one flange 66 protruding laterally
of the axis. In the embodiment shown in FIGS. 1 and 2, each segment
is a rigid element comprising two spaced flanges 66. Tubular
resilient couplings 72 are disposed between each of the rigid
segments 40, along the longitudinal axis and preferably aligned
with the lumen of the segments.
The flanges 66 each have at least one passage 74 for receiving a
control line 50. One end 76 of the control line is fixed to the
flange of a segment closer to the distal end 82 of the appendage.
The control line passes freely through the flange(s) of each of the
segments between this more remote segment and the proximal end 80.
Means are provided for applying tension to the control line 50.
Provided the tension applied to the control line(s) is laterally
unequal relative to the axis 64, the appendage 30 bends laterally
toward the control line having the greater tension due to
foreshortening of the lateral side of the appendage along which
this control line passes. Whereas the coupling between the segments
is resilient, the arm bends smoothly, accurately and
continuously.
Depending on the task required, the appendage can be arranged to
bend only in one direction (requiring only one control line),
returning resiliently when tension is released. Preferably however,
the segments 40 have a plurality of passages distributed around the
axis 64, and the device comprises a plurality of control lines 50,
whereby the appendage is bendable in opposed directions by tension
on selected ones of the control lines.
Similarly, depending on the task required, the appendage can be
arranged to have sections which vary in their susceptibility to
bending. It may be desirable, for example, to have a relatively
stiffer proximal section for general positioning and a relatively
flexible distal section for fine positioning. Sections can be
included which are not controllably bendable, and are either
flexible or rigid. As one example, when attempting to fish an
appendage of this type through branching conduits or the like, it
may only be necessary to controllably bend the extreme distal end
for guiding the appendage into a desired branch, after which it can
be pushed. This can be accomplished by varying the dimensions and
the flexibility of the joints between segments as well as the
segments themselves.
A preferred means for varying flexibility is to vary the length of
the spring or other resilient coupling between the segments. For
example, shorter (stiffer) connections can be provided near the
proximal end or base, and longer (more flexible) connections can be
provided approaching the distal end, where greater flexibility and
susceptibility to bending is desired. In the event a continuous
length of spring is used along the appendage, the segments can be
positioned at appropriately varying spacing along the spring, e.g.,
by screwing the segments along the helical pitch of the spring, and
fixed in place.
The control lines can be arranged in ranks for controlling groups
of the segments or even individual segments, at different distances
from the proximal end 80. In that case at least one rank 92a (See
FIG. 13) of control lines is fixed to a relatively more proximal
segment than at least one other rank 92a (see FIG. 13) of control
lines. In order to combat the tendency of the appendage to begin
bending at the more proximal joints, the more proximal sections
and/or the couplings between the more proximal sections can be made
stiffer by being larger and heavier, and/or coupled by stiffer
resilient couplings than the more distal sections. Another means
for varying the bending proclivity of the joints along the
appendage is to vary the lateral spacing between the axis and the
point at which the control lines pass, a relatively more powerful
bending force being produced by a relatively greater lateral
spacing of the control lines.
In order to allow passage of conduits such as electrical wires,
fluid lines, tools and the like, the central axis 64 of the
segments 40 have an access opening, and the resilient couplings 72
between the segments are hollow. In a preferred embodiment, the
couplings comprise helical springs 94, and the segments 40 each
comprise a rigid tube 96 disposed along the axis and at least one
flange plate aligned perpendicular to the tube. The springs 94 are
coupled to the rigid tubes 96 of adjacent ones of the segments,
either wrapping around the outer surface of the portion of tube 96
which protrudes beyond the flange plate, or being compressed into
the lumen of the tube. Each segment 40 can have two flange plates,
the rigid tube protruding from the flange plates at opposite ends
of the segment with the spring wrapped thereon. In FIGS. 1 and 2
the segments 40 are of different lengths along the appendage or
arm, at least some of the segments at a more proximal position
along the arm having a greater spacing between the flange plates
than segments at a more distal position. A variation in the
stiffness of the resilient couplings can be achieved by using
thicker spring wire, shorter axial spring lengths, etc., for the
proximal couplings as compared to the distal ones. To increase
stiffness, selected joints can have plural springs disposed inside
one another, or a spring joint can be made stiffer by interposing
another resilient material such as a length of rubber or plastic,
or even a metal spring bar. In these ways, the bending proclivity
along the appendage can be chosen as appropriate to the specific
task of the appendage.
Helical springs are preferred where it is desirable to leave open
the lumen. The helical springs 94 forming a resilient coupling
between the segments preferably are so-called "closed" springs. The
springs are wound such that adjacent turns of the springs rest
against one another at rest. Accordingly, the adjacent turns 102 on
a side of the appendage facing toward a bending radius remain in
direct contact, defining a constant length regardless of changes in
control line tension, while the turns 104 on the side of the
appendage facing away from the bending radius separate, to allow
bending. This aspect of the invention is illustrated in FIGS. 3 and
4. The same reference numerals have been used throughout the
drawings to identify comparable parts in the respective embodiments
of the inventions. When at rest (FIG. 3), the coils of the spring
abut, and when curved (FIG. 4), the coils of the spring on the
outside of the curve separate. However, whereas the coils on the
inner side of the curve remain in abutment, the appendage as a
whole is neither foreshortened by application of tension to the
control lines, nor elongated upon release of tension. This feature
improves control of the position of the distal end 82 of the
appendage, which for example can hold a tool.
FIGS. 5-7 illustrate some alternative forms of segments. The
illustrated segments in each case comprise two spaced flange plates
66, carried on a rigid spacing structure such as a tube, brace or
series of braces, whereby each segment is a rigid element. The
segments can be made, for example of polycarbonate or a similar
relatively rigid material. The segments can also be defined by
other shapes, provided a passage for a control line spaced
laterally of the axis is provided. One possible segment is a simple
tube or cylinder having grooves or holes spaced laterally from the
center and running parallel to the axis for carrying the control
lines. It is also possible to make the segments themselves
resilient, e.g., by use of a flexible material to space the
flanges. A more flexible segment or joint results in an overall
more sinuous and flexible arm, at the expense of accuracy of
positioning control. A smaller segment, especially a short segment
only a single flange, provides relatively greater flexibility than
a larger one with spaced flanges, due to the fact that more springs
are required over a given length for smaller segments than larger
ones, and retains good accuracy of control.
The triangular flange plate segment 106 in FIG. 5 is provided with
three passages 74 for control lines 50, and a central opening 62.
Instead of a tube for spacing the flange plates, a rigid segment
structure is provided by braces 108 at the apices of the flange
plates, associated with each of the control line passages 74. This
arrangement is useful in particular for the segment which forms the
distal terminus of the control lines, since the longitudinal
tension on the control line tending to pull the segment into a
curved orientation is resisted in each case by an associated brace
108. Preferably, the terminus of the control lines is on the
distal-side flange 66 of the respective segment, but the terminus
could also be on the proximal side or at an intermediate point.
FIG. 6 illustrates a segment 112 arranged to bend in only one
direction. In this segment the brace 108 between the flange plates
can be a solid member or a hollow one, e.g., a tube. The helical
spring for coupling the segments (not shown in FIG. 6) can be
wrapped over the protruding end 114 of the brace 108. Whereas the
passage 74 for the control line is laterally spaced from the
coupling defined by the spring and the brace, an arm 30 using this
form of segment bends toward the control line when tension is
applied, or straightens to a point defined by the connecting
springs 94 when tension is released. This form of segment is
advantageous in connection with an application such as the
movable-mandible mask shown in FIGS. 9 and 10.
In an embodiment with a single control line, the springs provide
the means for recovering when tension is released. By using shorter
and thicker springs, the recovery can be positive. The springs can
be arranged to return the appendage to a straight line or a curved
line, either in the same direction as the bend or in the opposite
direction, past the centerline.
FIG. 7 illustrates a particular arrangement of the holes 74
provided for passage of the control lines. This form of segment is
particularly useful where the appendage is cantilevered, or
oriented substantially horizontally, requiring tension on the upper
control lines simply to hold the appendage against drooping under
the influence of gravity. Assuming the flange is a regular pentagon
as shown, the uppermost control line is centered over the axis 64.
The side lateral control lines and the lower control lines are
placed slightly higher than the respective line between the axis 64
and the corresponding apex of the pentagon. Accordingly, the
pattern of control lines is shifted vertically relative to the axis
64, giving the operator additional mechanical advantage in
overcoming the tendency of the appendage to droop. Of course, a
vertically shifted pattern can also be provided on other flange
shapes than pentagons, e.g., round, square, triangular, etc.
In FIG. 7, not only is the pattern of control lines shifted
vertically, but the passages are not equally distributed. More of
the control lines are disposed above the longitudinal axis 64
(specifically three control lines) than below it (two). This also
makes it easier to control the horizontally oriented arm. In a
suitably resilient arm it may be possible to eliminate all the
control lines below the axis 64, allowing gravity to bend the arm
downwardly when needed.
Of course, in many instances the appendage need not be cantilevered
and a symmetrical arrangement of the control wires is appropriate.
The invention may be particularly useful, for example, as a
manipulating tool in a zero gravity space environment or
underwater, where gravity is less of a problem.
At least three control lines are needed to enable curving of the
appendage in any selected direction. However, curvature in one
direction or in limited directions may be adequate in many
instances. For example, where the capability exists to rotate the
arm around its longitudinal axis, bending in one plane would enable
positioning of the distal end at any point within a substantially
spherical envelope. FIG. 8 illustrates the application of the
invention to a form of medical instrument 120 under such
circumstances. The arm 30 in this case provides a steerable
conduit, for example to admit an endoscope or laparoscope, which
enables the operator to curve the distal end 82 to reorient a
viewing apparatus or to steer the arm for advance through a body
passage. Whereas the operator can release tension and rotate the
arm, curvature in one direction is adequate in this case. Of course
it is also possible to provide for controlled curvature in two
opposed directions or in any direction, by use of the required
number of control lines 50.
In FIG. 8, a pivoting handheld tool 122 is coupled to the proximal
end 80 of the arm 30 by one of two tip portions 124, and the
control line 50 is coupled to the other. By manually bringing
together the finger grips 126 of the tool, the tip portions 124 are
forced apart, thus exerting tension on the control line 50. The
control line passes freely through the segments of the arm to an
attachment at a segment near the distal end. The arm can be
arranged to curve from a straight orientation as shown in solid
lines, to a curved orientation 130, shown in dashed lines.
Alternatively, the rest position can be curved opposite the
direction of curvature, as shown in dash-dot lines 140, enabling
the arm to be oriented as required in two opposite directions,
while only requiring one control line 50.
The embodiment according to FIG. 8 can be arranged with a plurality
of relatively more rigid segments 40 separated by relatively more
flexible tube sections 72. The control line can run along a groove
in the outer edge of the segments, or through passages spaced from
the edge. A flexible sheath 142 is preferably provided on the
outside of the arrangement, with means provided to allow the
control line to move under the flexible sheath.
In FIG. 9, a plurality of appendages 30 are provided on a mask 150,
for simulating movable mouth parts 152 on an alien or humanoid
monster. The mask is made of an elastomeric skin material disposed
on a frame as shown in FIG. 10, including a number of movable
appendages 30 according to the invention, which can be controllably
curved, e.g., inwardly toward the mouth, by application of tension
to respective control lines, or released to a rest position upon
release of tension. The control lines can be run through the
material of the mask, for example in embedded guide tubes, to a
convenient location for the application of tension. Guide tubes
such as Bowden wire tubes can be attached adhesively to the mask,
for routing the control lines to a suitable control location. A
structure can be provided, for example, to exert tension on the
lines when the wearer flexes his or her jaw behind the mask.
Alternatively, an electromagnetic actuator is possible, or the
control lines may be coupled by a Bowden wire arrangement to a
handheld caliper-like manual controller.
The underlying structure 151, as shown in FIG. 10, forms a
relatively rigid base. The respective appendages 30 have proximal
segments 162 which are attached to rigid mask structure 151, with
the control lines routed through structure 151 to the interior.
Each of the appendages can have one control line, using segments
substantially as shown in FIG. 6, coupled by open helical springs.
The segments are arranged such that when tension is applied, the
appendages foreshorten and curve inwardly as if pulling toward the
mouth area. Upon releasing tension, the appendages return to a rest
position defined by the springs, which can be straight or curved. A
plurality of control lines can also be used, for more extensive
positioning control.
This is but one example of the use of the invention for simulation
of the appendages of living things. Other possibilities include the
trunk of an elephant, the tentacle of an octopus, fingers, hands,
antennae, tails, tongues, etc. The appendage is such that by
applying a skin-like surface material or sock over segments
dimensioned to approximate the skeletal members of a human or
animal, a convincing mimicry is achieved. This mimicry is
especially effective in connection with sinuous shapes, but can
also apply to more jointed human and animal parts.
FIG. 11 illustrates one alternative for an automated and/or
electromechanically driven arrangement. In this embodiment three
control lines pass from a proximal segment 162 mounted rigidly on a
drive box 164, to motors and controls mounted inside. Each control
line has a motor 166 for rotating a threaded shaft 168 carrying a
nut 170 to which the respective control lines 50 are attached. The
three control lines are independently positionable in this manner,
and assuming the three lines are distributed around the axis of the
arm, the arm can be curved in any direction. A microprocessor
controller 172 is coupled to drive the motors via suitable drivers.
The motors preferably are stepping motors and/or are geared for
accurate displacement of the control lines over small spans for
setting the distal end 82 to predetermined positions, which can be
stored in the microprocessor memory. Limit switches (not shown) can
be provided to reference each movable nut to a zero point.
Alternatively, a reference position of the arm 30 can be defined by
manually controlling the arm to place the distal end at a
predetermined point, and subsequent movements made relative to the
reference position.
Other forms of drive unit are also possible. For example, motors
rotating spools or crank arms to which the control lines are
attached is another possibility. The drive can also employ
pneumatic or hydraulic cylinders for applying tension to the
control lines, etc.
The invention is also applicable for manual drive, and makes an
interesting toy. The proximal segment is mounted to a base 182
which can be securely positioned against tension exerted by the
operator on the control lines 50. The base can be adapted to be sat
upon or knelt upon by the user. The control lines are preferably
attached at spaced points on one or two control handles 184 as
shown in FIG. 13. By pulling on the control handle while canting
the control handle relative to the base 182, unequal tension is
exerted on the control lines, and the arm is curved in any
direction selected as a function of the specific cant of the handle
relative to the base.
FIG. 12 shows another form of segment 192, which comprises easily
assembled and disassembled parts, which makes this version useful
in connection with a toy. The flange plates have central holes
including a locking structure such as a dovetail mortise 194,
mating with complementary structures 196 on the tube 198 which
spaces the flange plates. A snap fit is preferred, whereby the
device can be assembled by the user. As in FIG. 7, the flange
plates according to this embodiment have passages for ranked
control lines, offset vertically from positions at which the
control lines would be equiangular around the center axis. Segments
of this type can be attached using flexible connectors such as
springs.
FIG. 13 illustrates an embodiment wherein the control lines are
ranked. The more proximal segments 202 are relatively larger in
diameter and are coupled by relatively stiffer and/or shorter
springs. These segments are controlled using one set 204 of three
or more control lines, which terminate at a distal one 206 of the
larger segments. The remaining segments 208 proceeding to the
distal end 82 of the arm, are smaller and coupled by relatively
more flexible springs. The distal segments 208 are independently
controlled using a group 210 of three or more control lines. This
arrangement provides strength and control in the proximal section,
for carrying and grossly positioning the arm, as well as dexterity
in the distal section. Preferably, the ranked segment arrangement
is used together with a variation in the stiffness of the resilient
couplings, the more proximal rank of segments being more stiffly
coupled than the distal rank of segments. This variation can be
achieved by using heavier and/or axially shorter springs in the
proximal rank than in the distal rank.
The control lines 210 for the distal segments 208 are disposed
radially inwardly toward the axis, and those 204 for the proximal
sections 202 are disposed radially outwardly from the axis, the
control lines running parallel. Attaching the proximal control
lines on the outside provides additional leverage in positioning
the arm by application of tension. In a manual version of this
embodiment, each set of control lines can be attached to a handle
184 which can be pulled and/or tilted relative to the base and the
fixed proximal segment 162, for exerting unequal tension. Whereas
the ranked controls are independently operable, the arm of FIG. 12
can be formed into a compound bend, with the proximal rank bent in
one direction and the distal rank in another direction.
With a manually operated arm, the controls are generally limited to
two ranks, operable with a control handle for each or the user's
hands. An automated control advantageously can have a larger number
of ranks. The control lines for the more proximal ranks are
arranged along the outer portions of the proximal flange plates,
with the more distal ranks placed radially inward, running through
the proximal segments to their respective connections of segments
located closer to the distal end of the arm.
The invention is subject to wide variations. For example, although
the proximal segments are generally larger, not all the segments
need be of the same length and it is possible that using longer
distal segments may be appropriate for some applications, such as
spray painting, wherein a sweeping distal motion may be needed to
move a spray head over a path. Additionally, the invention can be
applied to intermediate joints or elbows, as well as to the distal
end of an automated appendage. The invention is also apt for a wide
variety of specific applications, only a few examples being
discussed herein.
FIG. 14 illustrates application of the invention to a toy 220 used
for aiming a garden hose 224. A joystick-like manual control 222 is
coupled to the base 182 of the device for operating the control
lines. The segments, shown in phantom lines, are progressively
smaller leading to the free end, and are connected by springs
leaving a lumen of sufficient size to receive the garden hose 224.
The appendage portion of the toy is covered by a sock or similar
skin 225, stretched over the segments. Alternatively, the segments
can be potted in a soft foam plastic or the like. Whereas critical
positioning is absolutely necessary in a garden hose aiming toy,
the springs can be open springs as shown in FIG. 15, or closed
springs as shown in FIG. 16.
FIG. 16 illustrates an embodiment wherein the control lines are
carried in sheaths 232 extending through the segments 40, or at
least protruding from the ends of the segments. The sheaths 232
preferably are flexible and attached to the segment flanges by
adhesive, being of a material similar to bicycle brake cable
sheathing. The sheaths 232 have the further aspect of limiting the
minimum bending radius which can be achieve by tension on the
control lines. As shown in FIG. 16, when the appendage is curved to
the point that the sheaths 232 of adjacent segments on the inside
of the curve come into abutment, the appendage cannot be curved
further. FIG. 17 achieves a similar limitation on the minimum
bending radius by means of spacers 242 provided on the ends of the
segments, which contact the adjacent segment to define the minimum
radius. The segments can have such spacers on one side only, or on
both sides as shown.
FIG. 18 is an example of an arrangement wherein the control lines
are ranked, but the different ranks are materially different forms
of appendage. FIG. 18 is a partial cutaway view showing application
of the invention to simulate a human hand. The fingers are
simulated by separate appendages 30 substantially as discussed
above. The segments can be dimensioned similarly to the finger
bones of the human hand, thus simulating the knuckles in the
fingers or phalanges. In the metacarpal area 252 (i.e., in the palm
portion of the hand), the separate phalange appendages are joined
at a one or more proximal ranks so as to be bendable in at least
one plane as a unit, thus simulating natural grasping motions. Four
fingers can be mounted on metacarpal segments 254, or pairs of two
fingers can be mounted on metacarpal segments in a similar manner.
Of course it is also possible to extend the series of segments 30
separately from the phalanges to the carpus, as characteristic of
the bones of human hands. Preferably, the metacarpal segments 254,
whether separate or joined as shown, are operably via a separate
rank of control lines, thus enabling the fingers to be flexed or
extended without also bending across the palm, and vice versa.
FIG. 19 is a partially cut away elevation view showing an
alternative form of medical instrument 262 having a preferential
distal bending area 266. This instrument is provided with a less
flexible or less controllable proximal section 264 and a very
flexible extreme distal end 266, for guiding the instrument. The
instrument is useful for procedures such as bronchial suctioning,
wherein it is necessary to guide a suction apparatus through
branching bronchial passages. The user can readily select between
passages at a branch by diverting the distal end 266 of the
instrument using unequal control line tension.
The instrument of FIG. 19 is preferably constructed of a
substantially continuous flexible plastic, having segments 270
embedded in a plastic body 268 during molding. The segments, shown
in dotted lines in FIG. 19, are more closely spaced at the less
flexible proximal end 264, and less closely spaced at the distal
end 266, where preferential bending is desired.
FIG. 20 illustrates another embodiment of a toy 282. In this
arrangement the appendage comprises a continuous body 284 of soft
plastic such as foamed polyurethane. The control lines extend
through openings running along the length of the appendage, which
may be strengthened by compressible guide tubes 286 or by spaced
lengths of non-compressible guide tubing. Paths for the control
lines can be formed by displacing the control lines in the potting
material before it has fully set, to disengage the control lines
from the potting and/or to enlarge the openings for the control
lines. A rigid segment plate 288 is provided near the distal end
for attachment of the control lines. A soft bulb 292 covers the
rigid distal segment plate 288, to avoid injury. This toy is a form
of soft boxing toy, intended to allow two participants to assume
closely facing positions and to control their respective soft
appendages to strike at one another.
The invention having been disclosed, additional variations will
become apparent to persons skilled in the art. The invention is
intended to cover not only the exemplary arrangements discussed
herein, but also a reasonable range of equivalents. Reference
should be made to the appended claims rather than the foregoing
examples, in order to assess the scope of the invention in which
exclusive rights are claimed.
* * * * *